Hybrid vigor is a real phenomena, and crossing the most disparate cultivars are going to result in the craziest results. Most stains bred locally will tend to become more homogenized, as the gene pool become mixed, diluted....
Finding new genes, fresh blood becomes the imperative.
That's why I enjoy trying to reach across the world and find something unique or different, than what's circulating locally, then breed them together, and watch the magic happen.
I would much rather have an f1 from a good, solid hobby breeder, than the leftovers of someone I've never met, or don't have any connection with. Because even the most elite breeders are not going to dispense their motherlode, it's simply not going to happen..
If your looking for elites, then the best thing to turn too is clones, IMO. But as for seeds, I think getting f1's, getting good mature beans from choice females is what matters most. I just see far too many obvious subpar beans circulating in seed banks. It's like a plague, people will sell you anything.
I always wonder how much of the genetic code actually gets carried along, how much is missing, when a bean looks immature.